The United Nations High Commissioner for Refugees has provided a highly critical assessment of Labor's plan to send 600 asylum seekers to Manus Island.

In a letter to the Federal Government, António Guterres says PNG does not have the capacity to shoulder the responsibility of processing asylum seekers.

He says the Government has indicated it will be handing legal responsibility to PNG authorities, but points out there is no effective legal or regulatory framework in the country to deal with refugees.

Mr Guterres says there are no immigration officers in PNG with the skills to assess refugee applications and the Government's so-called " no advantage" is ambiguous because there is no average time for resettlement.

Mr Guterrers' warning came as the Government confirmed it had not begun assessing any refugee claims for asylum seekers who have arrived by boat since the offshore processing deal in August.

A spokesman for Immigration Minister Chris Bowen says all new arrivals, including those who are still in Australia, are not given any advantage over asylum seekers in overseas refugee camps.

The Immigration Department confirmed this morning that it had transferred its eighth group of people to Nauru, with 23 Sri Lankans and 17 Iraqis arriving from Christmas Island.

Meanwhile Australian Human Rights Commission president Gillian Triggs has just returned from a UN fact-finding mission on Christmas Island.

She says there were problems with overcrowding and a lack of support facilities at the asylum seeker facility.

"I think the facilities for a relatively short period of four to six weeks transfer assessment are adequate for modest numbers," she said.

"The great difficulty is that the numbers are rising and numbers of families are rising, and that is where what would appear to be appropriate facilities become crammed and overcrowded facilities."

Ms Triggs says there are approximately 2,000 asylum seekers at the facility.

"The numbers wax and wane of course depending on how many are taken off to Nauru, how many come into Australia and they were expecting several hundred more as I left," she said.

"They are near capacity, but this coming group of 300 or 400 people is going to really stretch them and place enormous strain on the families in the particular camp known as Aqua."

Nauru concerns

Ms Triggs says the people she spoke to were concerned they would be transferred to Nauru.

"We asked a lot of questions. Obviously I'm there to look at the human rights standards and the 150 or so people I talked to either in groups or individually almost invariably were very grateful for the facilities and their treatment," she said.

"But their enormous mental anxiety lay with the fear that they would be transferred to Nauru; that their assessment would not take place for some months and would not be over for many years."

A spokeswoman at the Immigration Department said one person in the Nauru centre was involved in a self-harming attempt on Thursday morning.

He was assessed by medical staff at the centre and cleared of all physical injuries.

Ms Triggs says in spite of the recent Government changes, relatives of those on Christmas Island are not deterred.

"When I asked them had they known of the Nauruan policy or offshore processing policy, would they still have come, overwhelmingly the answer is that they would have done," she said.

"Now, I wasn't entirely prepared for that answer and I have to be careful in saying that I did interview only 150 of 2,000 people.

"I think they feel safe in Australia and they basically believe that the Australian Government will ensure that they continue to be safe.

"They will put up with extraordinary conditions if they think at the end of the day they will have a fair assessment of their refugee status and settlement."

Mr Bowen's spokesman said the immigration network is coping.

Two more asylum seeker boats were intercepted near Cocos Islands this morning, with seven people on one and six on the other.

The asylum seekers will be given basic health and security checks on Cocos Islands before being taken to Christmas Island.